Glabralysins, potential New β-pore-forming toxin family members from the schistosomiasis vector snail biomphalaria glabrata

Biomphalaria glabrata is a freshwater Planorbidae snail. In its environment, this mollusk faces numerous microorganisms or pathogens, and has developed sophisticated innate immune mechanisms to survive. The mechanisms of recognition are quite well understood in Biomphalaria glabrata, but immune effectors have been seldom described. In this study, we analyzed a new family of potential immune effectors and characterized five new genes that were named Glabralysins. The five Glabralysin genes showed different genomic structures and the high degree of amino acid identity between the Glabralysins, and the presence of the conserved ETX/MTX2 domain, support the hypothesis that they are pore-forming toxins. In addition, tertiary structure prediction confirms that they are structurally related to a subset of Cry toxins from Bacillus thuringiensis, including Cry23, Cry45, and Cry51. Finally, we investigated their gene expression profiles in snail tissues and demonstrated a mosaic transcription. We highlight the specificity in Glabralysin expression following immune stimulation with bacteria, yeast or trematode parasites. Interestingly, one Glabralysin was found to be expressed in immune-specialized hemocytes, and two others were induced following parasite exposure

A Shift from Cellular to Humoral Responses Contributes to Innate Immune Memory in the Vector Snail Biomphalaria glabrata

International audienceDiscoveries made over the past ten years have provided evidence that invertebrate anti-parasitic responses may be primed in a sustainable manner, leading to the failure of a secondary encounter with the same pathogen. This phenomenon called " immune priming " or "innate immune memory" was mainly phenomenological. The demonstration of this process remains to be obtained and the underlying mechanisms remain to be discovered and exhaustively tested with rigorous functional and molecular methods, to eliminate all alternative explanations. In order to achieve this ambitious aim, the present study focuses on the Lophotrochozoan snail, Biomphalaria glabrata, in which innate immune memory was recently reported. We provide herein the first evidence that a shift from a cellular immune response (encapsulation) to a humoral immune response (biomphalysin) occurs during the development of innate memory. The molecular characterisation of this process in Biompha-laria/Schistosoma system was undertaken to reconcile mechanisms with phenomena

Time-resolved single-cell analysis of Brca1 associated mammary tumourigenesis reveals aberrant differentiation of luminal progenitors

Abstract: It is unclear how genetic aberrations impact the state of nascent tumour cells and their microenvironment. BRCA1 driven triple negative breast cancer (TNBC) has been shown to arise from luminal progenitors yet little is known about how BRCA1 loss-of-function (LOF) and concomitant mutations affect the luminal progenitor cell state. Here we demonstrate how time-resolved single-cell profiling of genetically engineered mouse models before tumour formation can address this challenge. We found that perturbing Brca1/p53 in luminal progenitors induces aberrant alveolar differentiation pre-malignancy accompanied by pro-tumourigenic changes in the immune compartment. Unlike alveolar differentiation during gestation, this process is cell autonomous and characterised by the dysregulation of transcription factors driving alveologenesis. Based on our data we propose a model where Brca1/p53 LOF inadvertently promotes a differentiation program hardwired in luminal progenitors, highlighting the deterministic role of the cell-of-origin and offering a potential explanation for the tissue specificity of BRCA1 tumours

Time-resolved single-cell analysis of Brca1 associated mammary tumourigenesis reveals aberrant differentiation of luminal progenitors

Abstract: It is unclear how genetic aberrations impact the state of nascent tumour cells and their microenvironment. BRCA1 driven triple negative breast cancer (TNBC) has been shown to arise from luminal progenitors yet little is known about how BRCA1 loss-of-function (LOF) and concomitant mutations affect the luminal progenitor cell state. Here we demonstrate how time-resolved single-cell profiling of genetically engineered mouse models before tumour formation can address this challenge. We found that perturbing Brca1/p53 in luminal progenitors induces aberrant alveolar differentiation pre-malignancy accompanied by pro-tumourigenic changes in the immune compartment. Unlike alveolar differentiation during gestation, this process is cell autonomous and characterised by the dysregulation of transcription factors driving alveologenesis. Based on our data we propose a model where Brca1/p53 LOF inadvertently promotes a differentiation program hardwired in luminal progenitors, highlighting the deterministic role of the cell-of-origin and offering a potential explanation for the tissue specificity of BRCA1 tumours

Evolutive and Functional aspects of immune memory in Invertebrates : the Schistosomiasis vector snail Biomphalaria glabrata as a new model organism ?

Le clade des invertébrés cristallise en 2017 de grandes problématiques sociétales à la fois économiques et sanitaires. En effet un certain nombre des organismes présent dans ce groupe phylétique sont des vecteurs des grandes pandémies infectieuses telles que le paludisme (Anopheles sp), Zika, Chinkungunya, Fièvre jaune, etc (Aedes sp), Chagas (Triatoma sp) ou encore la bilharziose (Biomphalaria sp, Bulinus sp). La compréhension du système immunitaire de ces organismes vecteurs doit aider la communauté scientifique à proposer des solutions pour réduire la transmission de toutes ces maladies sur le terrain. Biomphalaria glabrata est le vecteur unique de la Bilharziose intestinale (Schistosomamansoni) en Amérique Latine. Depuis un premier cas de résistance induite par une première infection en 1998, de nombreux travaux ont exploré la réponse immunitaire mémoire innée de cet escargot tropical d’eau douce. Dans le cadre de ce travail de thèse, différents aspects de cette immunité (également appelé priming, résistance acquise) ont été explorés, de la mise en place phénotypiques, aux bases moléculaires et cellulaires. En premier lieu,nous avons pu démontrer qu’elle était dépendante d’une bascule phénotypique (d’une réponse cellulaire d’encapsulation à une réponse humorale) et transcriptomique qui lui permet de mieux répondre lors d’une seconde infection. La spécificité de cette réponse est portée par la production de répertoire complexe de récepteurs et d’effecteurs immunitaire spécifiques qui sont capables de différencier jusqu’aux différents stades de développement parasitaire d’une même espèce de parasite. Nous avons également pu montrer que cette interaction dépendait de microARN circulants ainsi que de Biomphalysines, des ß-PFT acquises par transferts horizontaux depuis le monde bactérien. Enfin, cette résistance semble posséder une proximité avec l’immunité mémoire entraînée des cellules immunitaires innées des vertébrés en particulier sur la base des mécanismes moléculaires sous-jacent qui seraient liés chez Biomphalaria comme chez les Vertébrés à unereprogrammation épigénétique des cellules du système immunitaire innée.Invertebrates focus in 2017 among the major economical and societal issuesacross Earth. Some members are vectors of important infectious pandemic as malaria(Anopheles sp), Zika, Chinkungunya, Yellow fever, etc (Aedes sp), Chagas (Triatoma sp) andtrematodes (Biomphalaria sp, Bulinus sp). Comprehension of immune system of thesevectors has to help scientist to decrease transmission on endemic area. Biomphalariaexposed first failure to be reinfected following first infection as soon as 1998. In my thesiswe explore this immune priming (innate immune memory) and describe an immune shiftfrom cellular to humoral immune response both in phenotype and transcriptomic response.A specificity is handle by specific immune receptor and effector repertoire to distinguish upto different developmental stage of same parasite species. This interaction is alsodependent of mRNAs and Biomphalysin, a ß-PFT coming from bacterial kingdom. Finally,this resistance seems to look alike the trained immune memory of innate cells in vertebrates

Aspects fonctionnel et évolutif de l'immunité mémoire chez les invertébrés : l'escargot vecteur de la Bilharziose intestinale Biomphalaria glabrata comme nouvel organisme modèle ?

Invertebrates focus in 2017 among the major economical and societal issuesacross Earth. Some members are vectors of important infectious pandemic as malaria(Anopheles sp), Zika, Chinkungunya, Yellow fever, etc (Aedes sp), Chagas (Triatoma sp) andtrematodes (Biomphalaria sp, Bulinus sp). Comprehension of immune system of thesevectors has to help scientist to decrease transmission on endemic area. Biomphalariaexposed first failure to be reinfected following first infection as soon as 1998. In my thesiswe explore this immune priming (innate immune memory) and describe an immune shiftfrom cellular to humoral immune response both in phenotype and transcriptomic response.A specificity is handle by specific immune receptor and effector repertoire to distinguish upto different developmental stage of same parasite species. This interaction is alsodependent of mRNAs and Biomphalysin, a ß-PFT coming from bacterial kingdom. Finally,this resistance seems to look alike the trained immune memory of innate cells in vertebrates.Le clade des invertébrés cristallise en 2017 de grandes problématiques sociétales à la fois économiques et sanitaires. En effet un certain nombre des organismes présent dans ce groupe phylétique sont des vecteurs des grandes pandémies infectieuses telles que le paludisme (Anopheles sp), Zika, Chinkungunya, Fièvre jaune, etc (Aedes sp), Chagas (Triatoma sp) ou encore la bilharziose (Biomphalaria sp, Bulinus sp). La compréhension du système immunitaire de ces organismes vecteurs doit aider la communauté scientifique à proposer des solutions pour réduire la transmission de toutes ces maladies sur le terrain. Biomphalaria glabrata est le vecteur unique de la Bilharziose intestinale (Schistosomamansoni) en Amérique Latine. Depuis un premier cas de résistance induite par une première infection en 1998, de nombreux travaux ont exploré la réponse immunitaire mémoire innée de cet escargot tropical d’eau douce. Dans le cadre de ce travail de thèse, différents aspects de cette immunité (également appelé priming, résistance acquise) ont été explorés, de la mise en place phénotypiques, aux bases moléculaires et cellulaires. En premier lieu,nous avons pu démontrer qu’elle était dépendante d’une bascule phénotypique (d’une réponse cellulaire d’encapsulation à une réponse humorale) et transcriptomique qui lui permet de mieux répondre lors d’une seconde infection. La spécificité de cette réponse est portée par la production de répertoire complexe de récepteurs et d’effecteurs immunitaire spécifiques qui sont capables de différencier jusqu’aux différents stades de développement parasitaire d’une même espèce de parasite. Nous avons également pu montrer que cette interaction dépendait de microARN circulants ainsi que de Biomphalysines, des ß-PFT acquises par transferts horizontaux depuis le monde bactérien. Enfin, cette résistance semble posséder une proximité avec l’immunité mémoire entraînée des cellules immunitaires innées des vertébrés en particulier sur la base des mécanismes moléculaires sous-jacent qui seraient liés chez Biomphalaria comme chez les Vertébrés à unereprogrammation épigénétique des cellules du système immunitaire innée

First characterization of viruses from freshwater snails of the genus Biomphalaria, the intermediate host of the parasite Schistosoma mansoni

International audienceWe report the genome sequence and organization of five viruses infecting snails of both Biomphalaria glabrata and Biomphalaria pfeifferi, which are vectors of the intestinal schistosomiasis. Four viruses presented a polyadenylated positive single strand RNA genome encoding one or two large open reading frames (ORFs) flanked by untranslated region. Conserved protein motifs typical of the picorna-like virus superfamily were identified in these viruses but they all presented different genome organization. Phylogenetic analysis confirmed their assignment to this superfamily. The partially characterized fifth virus presented sequence similarity for Totiviridae, a family of non-polyadenylated double-strand RNA viruses. Virus distribution and relative abundance between the five strains of Biomphalaria originating from different geographical areas was determined. Our results provide valuable information of new viruses from Biomphalaria and pave the way for future studies dedicated to their impact on snail fitness and Biomphalaria/Schistosoma interactions

Specific Pathogen Recognition by Multiple Innate Immune Sensors in an Invertebrate

Detection of pathogens by all living organisms is the primary step needed to implement a coherent and efficient immune response. This implies a mediation by different soluble and/or membrane-anchored proteins related to innate immune receptors called PRRs (pattern-recognition receptors) to trigger immune signaling pathways. In most invertebrates, their roles have been inferred by analogy to those already characterized in vertebrate homologs. Despite the induction of their gene expression upon challenge and the presence of structural domains associated with the detection of pathogen-associated molecular patterns in their sequence, their exact role in the induction of immune response and their binding capacity still remain to be demonstrated. To this purpose, we developed a fast interactome approach, usable on any host-pathogen couple, to identify soluble proteins capable of directly or indirectly detecting the presence of pathogens. To investigate the molecular basis of immune recognition specificity, different pathogens (Gram-positive bacterium, Micrococcus luteus; Gram-negative, Escherichia coli; yeast, Saccharomyces cerevisiae; and metazoan parasites, Echinostoma caproni or Schistosoma mansoni) were exposed to hemocyte-free hemolymph from the gastropod Biomphalaria glabrata. Twenty-three different proteins bound to pathogens were identified and grouped into three different categories based on their primary function. Each pathogen was recognized by a specific but overlapping set of circulating proteins in mollusk's hemolymph. While known PRRs such as C-type lectins were identified, other proteins not known to be primarily involved in pathogen recognition were found, including actin, tubulin, collagen, and hemoglobin. Confocal microscopy and specific fluorescent labeling revealed that extracellular actin present in snail hemolymph was able to bind to yeasts and induce their clotting, a preliminary step for their elimination by the snail immune system. Aerolysin-like proteins (named biomphalysins) were the only ones involved in the recognition of all the five pathogens tested, suggesting a sentinel role of these horizontally acquired toxins. These findings highlight the diversity and complexity of a highly specific innate immune sensing system. It paves the way for the use of such approach on a wide range of host-pathogen systems to provide new insights into the specificity and diversity of immune recognition by innate immune systems

BgTEP: an antiprotease involved in innate immune sensing in Biomphalaria glabrata

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BgTEP: An Antiprotease Involved in Innate Immune Sensing in Biomphalaria glabrata

Insect thioester-containing protein (iTEP) is the most recently defined group among the thioester-containing protein (TEP) superfamily. TEPs are key components of the immune system, and iTEPs from flies and mosquitoes were shown to be major immune weapons. Initially characterized from insects, TEP genes homologous to iTEP were further described from several other invertebrates including arthropods, cniderians, and mollusks albeit with few functional characterizations. In the freshwater snail Biomphalaria glabrata, a vector of the schistosomiasis disease, the presence of a TEP protein (BgTEP) was previously described in a well-defined immune complex involving snail lectins (fibrinogen-related proteins) and schistosome parasite mucins (SmPoMuc). To investigate the potential role of BgTEP in the immune response of the snail, we first characterized its genomic organization and its predicted protein structure. A phylogenetic analysis clustered BgTEP in a well-conserved subgroup of mollusk TEP. We then investigated the BgTEP expression profile in different snail tissues and followed immune challenges using different kinds of intruders during infection kinetics. Results revealed that BgTEP is particularly expressed in hemocytes, the immune-specialized cells in invertebrates, and is secreted into the hemolymph. Transcriptomic results further evidenced an intruder-dependent differential expression pattern of BgTEP, while interactome experiments showed that BgTEP is capable of binding to the surface of different microbes and parasite either in its full length form or in processed forms. An immunolocalization approach during snail infection by the Schistosoma mansoni parasite revealed that BgTEP is solely expressed by a subtype of hemocytes, the blast-like cells. This hemocyte subtype is present in the hemocytic capsule surrounding the parasite, suggesting a potential role in the parasite clearance by encapsulation. Through this work, we report the first characterization of a snail TEP. Our study also reveals that BgTEP may display an unexpected functional dual role. In addition to its previously characterized anti-protease activity, we demonstrate that BgTEP can bind to the intruder surface membrane, which supports a likely opsonin role